The present invention relates to supercharger systems used with internal combustion engines and more particularly to centrifugal supercharger systems having variable speed drives.
Superchargers employed to boost the power of internal combustion engines are well know. The supercharger systems typically include an air compressor that pulls in intake air and compresses it prior to being fed into the engine cylinders. This allows for a greater power output relative to the same size engine without a supercharger. The air compressor is conventionally driven by a belt that connects to a pulley on the shaft of the compressor and a pulley on the crankshaft of the engine. There may also be a fixed ratio gear set between the compressor and camshaft in order to obtain one desired gear ratio. So the rotational speed and thus the amount of compression depends solely upon the engine speed.
In particular, supercharged engines have advantages when used in vehicles. The advantage with superchargers is that the engine can produce more power, so for a given desired power output, the engine with a supercharger can be smaller, thus generally lighter weight and having better fuel economy. The drawback is that the centrifugal supercharger system does not provide much increase in pressure for the intake air at low engine RPMs.
Some have attempted to resolve this problem. One attempt to overcome the drawbacks of a centrifugal supercharger system employed a continuously variable belt drive between the drive pulley and the driven pulley of the compressor in order to vary the drive ratio. It used a belt mounted on cone pulleys. A pair of cones on each pulley could be pushed together and pulled apart to vary the drive ratio for the belt. But this proved to be too complicated and unreliable.
Further, it is advantageous to have the centrifugal supercharger system operate without causing a discontinuity in the torque and horsepower. These types of discontinuities can cause the engine to surge or lug down, which is generally objectionable to vehicle occupants.
Thus, it is desirable to have a centrifugal supercharger system that overcomes the drawbacks of the conventional centrifugal supercharger system. In particular, it is desirable to have a system with a variable drive ratio, in order to improve an engine""s torque at low RPMs, while avoiding the cost, complexity and unreliability of previous attempts to produce such a system. And, preferably, the variable drive ratio does not cause discontinuities in the torque or horsepower output.
In its embodiments, the present invention contemplates a system for variably controlling the rotational velocity input to a supercharger compressor that is operatively coupled to an internal combustion engine. The system includes an input shaft adapted to couple to a rotating member of the engine, and a first planetary gear set including a first sun gear, a first ring gear, and a first planet carrier having a first set of planetary gears mounted thereon and meshing with the first sun gear and the first ring gear, with one of the first sun gear, the first ring gear and the first planet carrier rotationally coupled to the input shaft. The system also includes a clutch mechanism having a first portion that is rotationally fixed relative to the engine, and a second portion that is selectively rotationally fixed relative to the first portion, with the second portion being rotationally coupled to one of the first sun gear, the first ring gear and the first planet carrier that is not coupled to the input shaft. A one-way clutch is coupled between one of the first sun gear, the first ring gear and the first planet carrier that is coupled to the input shaft, and another of the first sun gear, the first ring gear and the first planet carrier that is not coupled to the input shaft. A second planetary gear set includes a second sun gear, a second ring gear and a second planet carrier having a second set of planetary gears mounted thereon and meshing with the second sun gear and the second ring gear, with one of the second sun gear, the second ring gear and the second planet carrier rotationally fixed to one of the first sun gear, the first ring gear and the first planet carrier that is not directly rotationally coupled to the input shaft. An output shaft is adapted to couple to an input shaft to a supercharger and coupled to one of the second sun gear, the second ring gear and the second planet carrier; and a controller selectively actuates the clutch mechanism.
The present invention further contemplates a method for controlling the input speed to a drive shaft of a supercharger pump coupled to an internal combustion engine comprising the steps of: receiving input torque from a rotating member of the engine; providing a gear set shiftable between a higher gear ratio and a lower gear ratio; providing a clutch for causing a shift between the higher gear ratio and lower gear ratio; variably controlling the clutch while shifting back and forth between the higher gear ratio and the lower gear ratio to provide a smooth transition in torque output for the internal combustion engine; and providing an output member coupled between the gear set and the supercharger pump.
Accordingly, an object of the present invention is to provide a supercharger system for an internal combustion engine that includes a two speed gearbox between the drive pulley on the engine and the driven pulley on the compressor.
Another object of the present invention is to provide supercharger system for an internal combustion engine that includes a two speed gearbox with a variable controlled clutch.
An advantage of the present invention is that an engine with a two speed supercharger drive system will allow for improved vehicle torque at low engine RPMs while maintaining its efficiency at high engine RPMs.
Another advantage of the present invention is that the two speed supercharger drive is a low cost and reliable system for providing improved engine performance.
A further advantage of the present invention is that the drive ratio of the supercharger can be changed without a sudden torque or horsepower discontinuity by variably controlling a shift clutch coupled to the gear set.